Effects of Increasing N and S Deposition from Oil Sands Development on Bogs
Indigenous peoples of northern Alberta had known about the existence of bitumen associated with oil sands long before Peter Pond’s first written account in 1778. Sun Oil Company invested $240 million to build the Great Canadian Oil Sands facility, where an open pit mine and an oil upgrader began producing 45,000 bbl/da in 1967. In 2001, Cenovus Energy’s Foster Creek plant became the first in-situ oil sands operation, using SAGD (Steam Assisted Gravity Drainage) technology. Oil sands development has steadily increased over time with total oil sands production reaching 171,084,241 m3 in 2019. Most of the oil produced from the oil sands region is exported to the US; since 2009, the US has imported more oil from Canada than from any other country.
Associated with oil sands development is the release of gaseous N and S compounds into the atmosphere, both from upgrader stacks and diesel fuel powered mine fleets. Over the past 20 years, N emissions from oil sands operations have steadily increased, while with the installation of scrubbers on upgrader stacks, S emissions peaked in 2009 and have been declining since. These gaseous N and S emissions ultimately are deposited on the region’s natural ecosystems in both wet deposition (as NH4+-N, NO3–-N and SO42--S) and dry deposition (mainly as NH3, NO2, HNO3/HONO, and SO2).
Since 2009, we have been monitoring bogs situated between 11 and 77 km from the center of oil sands development (midpoint between the Syncrude and Suncor upgrader stacks), quantifying N and S deposition using ion exchange resin collectors, C, N, and S concentrations in 10 plant/lichen species, concentrations of NH4+-N, NO3–-N, SO42--S, DON and DOC in bog porewater, and plant community composition (Vitt group at Southern Illinois University) (Vitt et al. 2020, Wieder et al., in review, Environmental Monitoring and Assessment).
This research has been supported by the Wood Buffalo Environmental Association and Alberta Environment and Parks Oil Sands Monitoring Program.
Experimental N Addition to a Bog and a Poor Fen at the Mariana Lake Peatland Complex
To experimentally assess peatland responses to increasing atmospheric N deposition, we added N in simulated rainfall to a bog and a poor fen in the Mariana Lake peatland complex, Alberta. We added N to replicated plots at rates of 0, 5, 10, 15, 20, and 25 kg/ha/yr, with control plots receiving no water of N. Of the many responses observed, two were especially important in both the bog and poor fen. Increasing N deposition led to a change in plant species abundance and composition: the relative abundance of Sphagnum species changed and total Sphagnum abundance decreases, as a result of stimulated growth/cover of ericaceous shrubs that likely progressively shaded the moss layer. In addition, increasing N deposition resulted in a downregulation of biological N2-fixation, changing the pathways by which new N was added to the peatlands. Based on this research, we recommended a critical load of N for bogs and poor fens in Alberta of 3 kg/ha/yr (Wieder et al. 2019, Ecological Monographs and Wieder et al. 2020, Science of the Total Environment). This research was supported by CEMA, the Cumulative Environmental Management Association.
This was quite the project! See photos below. After the photos, there are links to videos of the Mariana Lake Peatland Study. Check them out!
Videos of Setup of the Mariana Lake Peatland Study
Below are links to five videos showing the Villanova and Southern Illinois University crews building the boardwalk through the poor fen and adjacent bog, setting up the N treatment plots, and on day 10 of work, carrying out of a trial run to make sure we could actually apply proscribed amounts of N to replicated experimental plots in this remote location.
The videos show three things: 1) there is a big difference between cinematographers and ecosystem scientists with a video camera, 2) the scale and scope of the fertilization study, and 3) senior researchers, full-time technicians, graduate students, and undergraduate field assistants working together in a spirit of mutual respect and camaraderie. I hope this has been a hallmark of our field teams over decades. Proud of them all!
Click on the bold, colored hyperlinks to go to the YouTube videos. Happy viewing.
Day 1 – Delivery of lumber, carrying lumber to through the upland to the edge of the poor fen. Beginning of boardwalk construction through the poor fen.
Days 2 and 3 – Boardwalk construction across the poor fen and into the bog.
Day 5 – Continued boardwalk and plot construction in the bog.
Day 9 – Finishing boardwalk and plot construction and building a storage shed where tanks, hoses, pumps, etc. were stored.
Day 10 – The big day!!! So now we have to see – can we have 2000 gallons of water delivered to the site and offloaded into into a holding tank, pump the water through the upland to the edge of the poor fen, to platforms in toe poor fen and bog with 50 gallon tanks for each N treatment level, and then pump water to the plots and simulate rainfall? This is a long video and some may be as exciting as watching paint dry (sorry). Fast forward may help…
Synoptic Survey to Assess Potential Effects of Oil Sands N and S Emissions on Bogs across the Oil Sands Region
Bogs and fens are a major feature of the northern Alberta landscape, covering 8,962 and 29,083 km2 of the 140,000 km2 Oil Sands Administrative Area. Most of this area is remote with few roads, making access to research sites a challenge. To complement the intensive bog monitoring and experimental N addition research described above, we wanted to evaluate potential effects of oil sands N and S emissions, and attendant N and S deposition, on bogs regionally.
With grant support from the Wood Buffalo Environmental Association (WBEA), we spent two lovely July days in 2013 visiting 19 remote bog sites spatially distributed within an 80 km x 80 km grid centered on the oil sands mining region. At each bog, we collected plant/lichen tissue samples and bog porewater samples. Sites were accessed by helicopter. We also collated N and S deposition data from ion exchange resin collectors at 23 sites (sites maintained by WBEA and by our group) to generate spatially interpolated maps of N and S deposition. For the lichens Evernia mesomorpha and Cladonia mitis, the moss Sphagnum fuscum, and the vascular plants Rhododendron groenlandicum and Picea mariana, tissue N and S concentrations were highest near the oil sands industrial center and were positively correlated interpolated N and S deposition. Porewater H+ and SO42--S, but not NH4+-N, NO3–-N or DIN, concentrations increased with proximity to the oil sands industrial center. Bog plant/lichen tissue chemistry may offer an effective tool for monitoring the spatial extent of elevated N and S deposition linked to oil sands development and may serve as harbingers of potential shifts in bog ecosystem structure and function (Wieder et al. 2016, Environmental Science & Technology).